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Commit e6caa602 authored by Minchan Kim's avatar Minchan Kim Committed by Vinayak Menon
Browse files

mm: Per process reclaim 



These day, there are many platforms available in the embedded market
and they are smarter than kernel which has very limited information
about working set so they want to involve memory management more heavily
like android's lowmemory killer and ashmem or recent many lowmemory
notifier.

One of the simple imagine scenario about userspace's intelligence is that
platform can manage tasks as forground and background so it would be
better to reclaim background's task pages for end-user's *responsibility*
although it has frequent referenced pages.

This patch adds new knob "reclaim under proc/<pid>/" so task manager
can reclaim any target process anytime, anywhere. It could give another
method to platform for using memory efficiently.

It can avoid process killing for getting free memory, which was really
terrible experience because I lost my best score of game I had ever
after I switch the phone call while I enjoyed the game.

Reclaim file-backed pages only.
	echo file > /proc/PID/reclaim
Reclaim anonymous pages only.
	echo anon > /proc/PID/reclaim
Reclaim all pages
	echo all > /proc/PID/reclaim

Change-Id: Iabdb7bc2ef3dc4d94e3ea005fbe18f4cd06739ab
Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Patch-mainline: linux-mm @ 9 May 2013 16:21:24
[vinmenon@codeaurora.org: trivial merge conflict fixes,
and minor tweak of the commit msg]
Signed-off-by: default avatarVinayak Menon <vinmenon@codeaurora.org>
parent 16ef9135

fs/proc/base.c

+3 −0
Original line number Diff line number Diff line
@@ -3162,6 +3162,9 @@ static const struct pid_entry tgid_base_stuff[] = { 
	REG("mounts",     S_IRUGO, proc_mounts_operations),

	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),

	REG("mountstats", S_IRUSR, proc_mountstats_operations),

#ifdef CONFIG_PROCESS_RECLAIM

	REG("reclaim", 0200, proc_reclaim_operations),

#endif

#ifdef CONFIG_PROC_PAGE_MONITOR

	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),

	REG("smaps",      S_IRUGO, proc_pid_smaps_operations),

fs/proc/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -199,6 +199,7 @@ struct pde_opener { 
extern const struct inode_operations proc_link_inode_operations;



extern const struct inode_operations proc_pid_link_inode_operations;

extern const struct file_operations proc_reclaim_operations;



extern void proc_init_inodecache(void);

void set_proc_pid_nlink(void);

fs/proc/task_mmu.c

+121 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/page_idle.h>

#include <linux/shmem_fs.h>

#include <linux/uaccess.h>

#include <linux/mm_inline.h>



#include <asm/elf.h>

#include <asm/tlb.h>
@@ -1642,6 +1643,126 @@ const struct file_operations proc_pagemap_operations = { 
};

#endif /* CONFIG_PROC_PAGE_MONITOR */



#ifdef CONFIG_PROCESS_RECLAIM

static int reclaim_pte_range(pmd_t *pmd, unsigned long addr,

				unsigned long end, struct mm_walk *walk)

{

	struct vm_area_struct *vma = walk->private;

	pte_t *pte, ptent;

	spinlock_t *ptl;

	struct page *page;

	LIST_HEAD(page_list);

	int isolated;



	split_huge_pmd(vma, addr, pmd);

	if (pmd_trans_unstable(pmd))

		return 0;

cont:

	isolated = 0;

	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);

	for (; addr != end; pte++, addr += PAGE_SIZE) {

		ptent = *pte;

		if (!pte_present(ptent))

			continue;



		page = vm_normal_page(vma, addr, ptent);

		if (!page)

			continue;



		if (isolate_lru_page(page))

			continue;



		list_add(&page->lru, &page_list);

		inc_node_page_state(page, NR_ISOLATED_ANON +

				page_is_file_cache(page));

		isolated++;

		if (isolated >= SWAP_CLUSTER_MAX)

			break;

	}

	pte_unmap_unlock(pte - 1, ptl);

	reclaim_pages_from_list(&page_list);

	if (addr != end)

		goto cont;



	cond_resched();

	return 0;

}



enum reclaim_type {

	RECLAIM_FILE,

	RECLAIM_ANON,

	RECLAIM_ALL,

	RECLAIM_RANGE,

};



static ssize_t reclaim_write(struct file *file, const char __user *buf,

				size_t count, loff_t *ppos)

{

	struct task_struct *task;

	char buffer[PROC_NUMBUF];

	struct mm_struct *mm;

	struct vm_area_struct *vma;

	enum reclaim_type type;

	char *type_buf;



	memset(buffer, 0, sizeof(buffer));

	if (count > sizeof(buffer) - 1)

		count = sizeof(buffer) - 1;



	if (copy_from_user(buffer, buf, count))

		return -EFAULT;



	type_buf = strstrip(buffer);

	if (!strcmp(type_buf, "file"))

		type = RECLAIM_FILE;

	else if (!strcmp(type_buf, "anon"))

		type = RECLAIM_ANON;

	else if (!strcmp(type_buf, "all"))

		type = RECLAIM_ALL;

	else

		return -EINVAL;



	task = get_proc_task(file->f_path.dentry->d_inode);

	if (!task)

		return -ESRCH;



	mm = get_task_mm(task);

	if (mm) {

		struct mm_walk reclaim_walk = {

			.pmd_entry = reclaim_pte_range,

			.mm = mm,

		};



		down_read(&mm->mmap_sem);

		for (vma = mm->mmap; vma; vma = vma->vm_next) {

			reclaim_walk.private = vma;



			if (is_vm_hugetlb_page(vma))

				continue;



			if (type == RECLAIM_ANON && vma->vm_file)

				continue;

			if (type == RECLAIM_FILE && !vma->vm_file)

				continue;



			walk_page_range(vma->vm_start, vma->vm_end,

					&reclaim_walk);

		}

		flush_tlb_mm(mm);

		up_read(&mm->mmap_sem);

		mmput(mm);

	}

	put_task_struct(task);



	return count;

}



const struct file_operations proc_reclaim_operations = {

	.write		= reclaim_write,

	.llseek		= noop_llseek,

};

#endif



#ifdef CONFIG_NUMA



struct numa_maps {

include/linux/rmap.h

+4 −0
Original line number Diff line number Diff line
@@ -12,6 +12,10 @@ 
#include <linux/memcontrol.h>

#include <linux/highmem.h>



extern int isolate_lru_page(struct page *page);

extern void putback_lru_page(struct page *page);

extern unsigned long reclaim_pages_from_list(struct list_head *page_list);



/*

 * The anon_vma heads a list of private "related" vmas, to scan if

 * an anonymous page pointing to this anon_vma needs to be unmapped:

mm/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -807,3 +807,16 @@ config HAVE_LOW_MEMORY_KILLER 
	  Say 'y' if you have a user/kernel low memory killer and thus you

	  want page allocator to provide sufficient time before it triggers

	  Out of Memory killer.



config PROCESS_RECLAIM

	bool "Enable process reclaim"

	depends on PROC_FS

	default y

	help

	 It allows to reclaim pages of the process by /proc/pid/reclaim.



	 (echo file > /proc/PID/reclaim) reclaims file-backed pages only.

	 (echo anon > /proc/PID/reclaim) reclaims anonymous pages only.

	 (echo all > /proc/PID/reclaim) reclaims all pages.



	 Any other value is ignored.